We propose the acquisition of an 800 MHz NMR spectrometer that will serve the research community of UCSF primarily with some service for researchers on other University of California campuses in Northern California. The research proposed for the new instrument will improve our capability to use multidimensional NMR experiments for determining high-resolution structures in solution primarily of proteins, nucleic acids, and complexes entailing proteins and nucleic acids, as a means of elucidating biological function. The additional sensitivity and resolution, as well as enhanced utilization of residual dipolar coupling measurements and pulse sequences incorporating transverse relaxation optimized spectroscopy (TROSY), afforded by the new instrument will not only increase through-put in structure determination, but it will permit determination of resonance assignments in regions which are currently ambiguous, enable additional structural restraints to be determined leading to higher quality structures, enable some structure determinations which have not been possible so far due to aggregation problems, and extend our ability to determine structures of biopolymers with molecular mass >30 kilodaltons.